Air filtration is primarily employed in commercial and residential heating, ventilation, and air cooling systems for the removal of atmospheric dust, and other undesirable airborne matter. Air filters associated with an indoor air quality (IAQ) system, for example clean the air by mechanically capturing airborne pollutants such as dust, pet hair, dander, pollen, etc, which have a relatively large size of more than 10 um. Conventional electronic air cleaners remove particles in a size range between approximately 0.3 um to 10 um. Such physical filtration approaches are limited in their effectiveness, because they do not remove smaller size contaminants such as biological contaminants and volatile organic compounds.
Photocatalysts having a strong sterilizing, deodorizing and air purifying effect have been employed in the context of air filters utilized in indoor air quality systems for air purification. One prior art approach, for example, employs an air cleaner with a photocatalyst carrying member, which is composed of a honeycomb-shaped structure. In this configuration, the photocatalyst carrying member is in contact with a lamp, which emits photons with a proper wavelength to activate a photocatalyst.
One of the problems associated with such a prior art approach stems from the fact that the limited area of the photocatalyst in the honeycomb-shaped structure is illuminated and activated by the lamp for air cleaning, which is an inefficient approach.
Another prior art technique locates a lamp to activate the photocatalyst in a direction perpendicular to the direction of air flow. A porous substrate with the light activated photocatalyst may be placed in front of the lamp. Therefore, only a portion of the light illuminating the porous substrate is employed to activate the photocatalyst and the light energy stemming from the porous substrate is typically wasted.
Based on the foregoing, it is believed that a need exists for an improved photocatalyst-based air purification apparatus and method for improving the usage efficiency of light energy employed to activate a photocatalyst, as described in greater detail herein.